烟气再循环实现低NOx排放的实验研究

实现高温空气燃烧技术的关键是控制燃烧区内的含氧体积浓度.建立了一套小型高温空气燃烧系统.采用炉外烟气再循环实现高温空气燃烧所需要的低氧环境.对烟气再循环对高温空气燃烧NOx排放特性的影响进行了实验研究,并分析了燃烧室的温度分布情况,总结了NOx及燃烧特性随烟气再循环率的变化的规律.     

蓄热式高温空气燃烧技术的应用(1)

简述了蓄热式高温空气燃烧技术的原理、技术优势以及应用前景,着重介绍我国在蓄热式高温空气燃烧技术领域的基础研究进展及应用情况.     

高温空气燃烧技术的特点与发展现状

通过对现今高温空气燃烧方面文献的总结,得到了高温空气燃烧技术及高温空气燃烧系统的特点、发展和国内外应用研究现状。并对高温空气燃烧的发展提出了自己的一点看法,期望高温空气燃烧能够实现大型化,结构简单化,以拓宽其应用领域。     

高温空气燃烧技术(HTAC)及其应用效果

高温空气燃烧技术是近十年来高速发展的一种新型燃烧技术，因同时具有高效、节能和低污染等特性，目前正得到越来越广泛的应用。本文介绍了高温空气燃烧技术的由来、工作原理、特点及应用效果，并分析了这种燃烧技术在我国的应用前景。     

高温空气燃烧技术的开发应用、技术优势及其展望

高温空气燃烧技术和高温空气气化技术是当前世界节能与环保领域中的两大新技术,二者均采用高于燃料着火点温度的高温空气作氧化剂或气化剂。介绍了利用蓄热式高温烟气余热回收装置和专门的高温空气发生器产生高温空气的方法,前者主要用于高温空气燃烧技术,后者主要用于高温空气气化技术。概括了高温空气燃烧技术和高温空气气化技术的应用状况,总结了其技术优势,并指出高温空气燃烧技术和高温空气气化技术符合中国国情,具有巨大的开发潜力和广阔的市场前景。     

陶瓷蓄热式换热器高温空气燃烧的实验研究

采用蓄热式换热器高温空气燃烧技术,建立了工艺有害气体高温分解系统;对以高温空气燃烧技术为理论依据的蓄热式换热器高温燃烧分解系统进行了实验研究;分析了其运行特征;探讨了蓄热周期对烟气与空气进出口温度变化特性、污染物排放浓度等参数的影响;提出了最佳换向周期,并指出短周期可以有效降低NOx的排放体积分数.     

燃烧参数影响高温空气燃烧特性的数值分析

高温空气燃烧技术具有高效节能和低NOx排放等多重优越性，是一种新型燃烧技术。为了深入研究高温空气燃烧机理和低氮氧化物排放特性，将湍流N—S方程与扩散燃烧模型和热力型NO生成模型相结合，研究了低氧浓度条件下，燃烧参数，如燃气供应量，过量空气系数，进口空气预热温度以及进口空气氧含量对燃烧的影响，为发展高温空气燃烧技术提供了理论依据。     

中小型燃气锅炉NO_x源头控制及低氮燃烧技术研究进展

介绍了燃气燃烧过程中热力型NO_x和快速型NO_x的生成机理,从对空气的预处理、对燃气和空气的混合分配两个方面综述了燃烧源头控制降低NO_x排放的技术,主要包括高温空气燃烧、柔和燃烧、浓淡燃烧、分级分段燃烧、脉动燃烧、烟气再循环等单一技术和旋流与富氧燃烧、烟气再循环与高温空气燃烧等组合技术;结合低NO_x原理,综述了低NO_x技术的实现形式,指出低NO_x燃烧技术的发展前景。     

连续蓄热燃烧技术在固体燃料加热炉应用探索

根据固体燃料燃烧的特点及高温空气燃烧技术原理,对连续蓄热燃烧技术在固体燃料加热炉上的应用进行了探索。搭建连续式蓄热固体燃料实验装置,对炉膛温度、烟气温度及助燃空气温度等参数进行测量分析,排烟温度可以控制在150℃以下,助燃空气预热温度低于高温烟气温度约100℃。当助燃空气预热温度波动30℃左右时,炉膛温度波动不高于3℃,可以满足多种加热工艺对加热精度的要求。测试结果表明,连续式高温空气燃烧技术可以应用在固体燃料加热炉上,通过对其烟气余热最大限度的回收,拓展了蓄热燃烧技术的应用领域。     

低NOx高温空气燃烧技术

低NOx高温空气燃烧技术将传统的低NOx燃烧技术与高温热式燃烧系统有地结合起来，具有热效率高、炉内温度分布均匀、NOx排放量低等特点。本文介绍了高温空气燃烧技术，重点分析了高温空气燃烧技术中的低NOx排放的原理，并对两种采用烟气再循环和分级燃烧技术的NOx高温空气燃烧器进行阐述。     

射流对高温空气燃烧过程中NO_x生成的影响

总结了燃料燃烧过程中NOx的生成机理和各种影响因素，并结合高温空气燃烧（High Temperature Air Combustion-HiTAC）的特点和射流的基本原理，研究了燃料和空气射流的卷吸作用对该燃烧方式NOx生成量的影响。为选择合理的设计与运行参数，实现该燃烧方式的超低NOx排放和高效节能，也为更好地在我国推广和应用这一先进技术提供理论基础。     

Diluted Air Combustion and NOx Emission in a HiTAC Furnace

CFD modeling of NOx emission via N₂O-intermediate mechanism was developed to predict the NOx formation in an experimental furnace equipped with high temperature air combustion (HiTAC) system. The good agreement between the predicted and measured results illustrates the superiority of using a N₂O-intermediate model in prediction of NOx emission during low peak temperature, which happens in HiTAC systems. Moreover, the CFD and measured results show that the flame volume as well as NOx emission significantly depends on temperature and oxygen concentration. Lower NOx emission was experimentally and numerically obtained at lower input oxygen concentration conditions.     

CFD study on influence of fuel temperature on NOx emission in a HiTAC furnace

The influence of the fuel temperature on NOx formation was investigated numerically. For this purpose CFD modeling of NOx emission in an experimental furnace equipped with high temperature air combustion (HiTAC) system was studied. The comparison between the predicted results and measured values have shown good agreement, which implies that the adopted combustion and NOx formation models are suitable for predicting the characteristics of the flow, combustion, heat transfer, and NOx emissions in the HiTAC chamber. Moreover the predicted results show that increase of the fuel temperature results in a higher fluid velocity, better fuel jet mixing with the combustion air, smaller flame and lower NOx emission.     

Thermal performance analysis on a two composite material honeycomb heat regenerators used for HiTAC burners

Honeycomb heat regenerators do not only reduce the fuel consumption in a high temperature air combustion (HiTAC) burning system but also provide the necessary high temperature of combustion air. A two-dimensional simulation model was developed to numerically determine the dynamic temperature and velocity profiles of gases and solid heat-storing materials in a composite material honeycomb regenerator. Consequently, the energy storage and the pressure drop are calculated and the thermal performance of honeycomb heat regenerator is evaluated at different switching times and loading. The model takes into account the thermal conductivity parallel and perpendicular to flow direction of solid and flowing gases. It considers the variation of all thermal properties of solid material and gases with temperature. Moreover, the radiation from combustion flue gases to the storage materials was considered in the analysis. The results are presented in a non-dimensional form in order to be a design tool as well. These analyses were applied on a regenerator made of two layers of ceramic materials, one is pure alumina and other is cordierite. This regenerator is contained in a 100 kW twin-type regenerative-burning system used for HiTAC. The effectiveness and the energy recovery rate were 88% and 72% respectively at nominal operating range of the regenerator and the pressure drop across the twin regenerator system was 1.16 kPa. The periodic steady state condition is reached after about 11 min and it takes only 2 min of operation until the temperature of combustion air remains above the self-ignition temperature that is required for HiTAC. Furthermore, these mathematical analyses show good agreement with experiments made on the same regenerator. In the experiments, the dynamic behavior of the heat regenerator operation was considered in order to compensate measurement readings for this effect.     

均热炉燃烧系统改造方案的数值模拟研究

应用高温空气燃烧技术改造传统均热炉燃烧系统，可以节约燃气的消耗率，提高炉内温度场的均匀性。本文通过数值模拟试验，研究了某厂均热炉应用高温空气燃烧技术改造后的炉内流场和温度场，从而提出了优化改造方案。     

The CFD Modeling of NOx Emission,HiTAC and Heat Transfer in an Industrial Boiler

NOx emission, heat transfer, and high temperature air combustion (HiTAC) in a boiler of Mobin Petrochemical Complex, Iran was numerically studied. The comparison between the measured values and the CFD predicted results showed good agreement, which implied that the adopted combustion and NOx formation models are suitable for correctly predicting characteristics of the heat recovery steam generation (HRSG) boiler. The predicted results show that NOx emission within the boiler depends highly on temperature, as well as oxygen concentration. Moreover, the influence of the equivalence ratio at a fixed air mass flow rate on the flame temperature and NOx formation has been investigated.     

Experimental study of the fuel jet combustion in high temperature and low oxygen content exhaust gases

The performance of high temperature air combustion (HiTAC) depends on the heat regenerator efficiency and on the way fuel is mixed with furnace gases. In this work, combustion of a single fuel jet of gasol (>95% of propane) was investigated experimentally. Experiments were carried out in steady-state conditions using a single jet flame furnace. The jet of fuel was co-axially injected into high temperature exhaust gases generated by means of a gas burner also fired with gasol. Thus, instead of highly preheated and oxygen depleted air, which was normally used by other researches for such studies, this work has used high temperature and low oxygen content exhaust gases as the oxidiser. A water-cooled fuel nozzle was used to control fuel inlet temperature. Influence of the oxygen content in the oxidiser, at temperatures of 860–890 °C, on the flame visibility and the reactants composition was investigated. The combustion of gasol in hot flue gases appeared to be very stable and complete even at very low oxygen concentration. The oxygen concentration in the oxidiser was found to have a substantial effect on flame size, luminosity, colour, visibility and lift-off distance. Reduced oxygen concentration increases the flame size and lift-off distance, and decreases luminosity and visibility. The HiTAC flame first became bluish and then non-visible at sufficiently low concentration of oxygen in the oxidiser. In this work, results are presented for the constant ratio between fuel jet velocity and velocity of co-flowing flue gases. This ratio was equal to 26.     

高温空气平焰燃烧过程的数值模拟

高温空气燃烧技术是一种新型高效低污染燃烧技术,而平焰燃烧是一种以辐射传热为主的传统工业炉窑燃烧技术,将二者相结合,进行了高温空气平焰燃烧过程的数值模拟研究,采用燃料深度给入方式成功实现了传统平焰预混或半预混燃烧向非预混燃烧的转变,并分析了高温空气燃烧技术与平焰燃烧相结合的可行性及其燃烧特性。     

高温空气燃烧技术的国际发展动态

2001年在意大利罗马召开的第四届高温空气燃烧与气化国际会议是对这项技术10多年的研究与应用的一个总的展示和检阅。综合论述了最新的国际发展动态，了解这方面的情况对于发展我国的燃烧技术和理论及其工程应用具有重要的意义。     

H2 – CH4 blending fuels combustion using a cyclonic burner on colorless distributed combustion

H₂ – CH₄ mixture fuels can be promising for reducing carbon-based emissions. However, because of higher pollutant emission (such as NO_X) problems during hydrogen combustion, a new combustion method can be favorable. Colorless distributed combustion (CDC) is emerging here. CDC enables ultra-low pollutant emissions along with reduced flame instabilities, combustion noise, improved combustion efficiency, etc. Considering those benefits, methane and the hydrogen-enriched methane (60% CH₄ – 40% H₂, 50% CH₄ – 50% H₂, 40% CH₄ – 60% H₂) fuels have been consumed using a cyclonic burner providing more residence time at an equivalence ratio of 0.83 under distributed regime. For the modelings, Reynolds Stress Model (RSM) turbulence model, the assumed-shape with β-function Probability Density Function combustion model, and P-1 radiation model have been selected. To seek CDC, the oxygen concentration in the oxidizer was reduced with N₂ or CO₂ diluent from 21% O₂ to 13% O₂ at an interval of 2%. The air and the fuel temperatures were kept constant at 300 K. Besides, for seeking high-temperature air combustion (HiTAC) conditions the oxidizer temperature was changed to 600 K to simulate flue gas recirculation. The results showed that the temperature distributions changed to be more uniform considerably with a decrease in oxygen concentration for all cases. CDC also provided a considerable decrease in NO_X and a favorable reduction in CO at a certain oxygen concentration. It has been concluded that CO₂ as the diluent was more effective for reducing temperature levels and NO_X levels due to its greater heat capacity.